1. Field of the Invention
The present invention relates to display systems and, in particular, to a display system that presents high density information taking into consideration priority of screen information and ease of use. Such a system is for use in, for example, air traffic control.
2. Description of the Related Art
Display systems for use in air control must present many pieces of information to air controllers. All pieces of information are not necessarily presented all the time. Frequency at which information is displayed is different from information type to information type. More specifically, the information presented on the air control display system is categorized into 1) information the air controller must constantly keep track of in detail, 2) information that requires no continuous tracking but must be still checked at intervals, and 3) information that must be checked if a change occurs in situation.
Known systems that present information in an integrated fashion display a plurality of pieces of information different in frequency of presentation, namely, priority using a plurality of displays. Such a system requires a large installation area because a plurality of displays must be installed. To verify all screen information, the air controller must take a view at a wide angle in comparison with the case in which a single display is used. Such a system is not very much satisfactory in terms of operability.
Another known display system provides a plurality of pieces of screen information on the screen of a single display apparatus in a window format. The window format presentation allows windows to be displayed in an overlapping state. A window presenting information having a low priority is presented behind a window of high priority. As necessary, the system may be operated to show the window of low priority in front. In the window format presentation, a particular window may be contracted or expanded in size as necessary.
Such a system is unable to immediately present information on a window presented behind another window. To reference the information, a front and back relationship of windows must be switched. The same switching operation must also be performed to reference a window that is hidden behind a particular window that has been expanded on the screen. The switching operation that must be frequently performed by each air traffic controller becomes one cause to an increase in the workload of the air traffic controller.
One of known display systems, aiming at the reduction of the controller workload, presents only windows of high priority and keeps, in a hidden state, windows of low priority unless a particular operation is performed. Although this display system maintains an excellent operability during normal operating conditions, an operation that is not usually performed must be performed to display information of low priority. An operation to present a window that is hidden as a result of expansion of another particular window must be still performed. This system is far from the one having improved general operability.
In summary, the known display systems have the following drawbacks.
Visibility of the screen information is reduced if a plurality of windows is concurrently presented. This is because overlapping windows present difficulty to the controller in viewing the screen information.
If one window is presented in a close-up fashion, another widow is hidden. The one window, selected and expanded in a close-up view, hides another window.
The controller has difficulty in watching and noticing a change in the state of each window. With windows overlapping each other, information is hidden and cannot be seen.
An operation using a mouse, etc. is complex. For example, to present a plurality of windows at the same time, the display system must be adjusted for a required portion of each window to remain appearing.
The display apparatus for use in air control has information the controller is occasionally forced to give up displaying because of limited screen space. This is because a single screen (window) is designed to present Information of minimum amount possible to reduce the frequency of switching of the windows, which could lead to an increase in the workload on the controller.